Gas Sensing and Structural Properties of a Nano-structure MoO3-based Hydrogen Sensor

Abstract

In this research, thin films of molybdenum trioxide were deposited on a glass substrate using Doctor Blade method. Ammonium Heptamolbudate tetrahydrate (NH4)6Mo7O24 powder is considered as a precursor to this study. Growth of the samples in three main directions of (020), (040) and (060) showed the formation of a layered structure and also the formation of α-phase of molybdenum oxide. In addition, scanning electron microscope imaging of the samples showed flat micro-capsule like structure. Furthermore, gas sensing properties of the fabricated structure were studied in expose to different concentrations of hydrogen gas. The highest and lowest sensitivities were reported about 16 and 91%, for 100 and 1000 ppm of hydrogen gas, respectively, which shows more sensitivity compare to previous studies. Moreover, the fabricated sensor exhibits good stability as well as repeatability for H2 gas detection.

Tapered Optical Fiber for Hydrogen Sensing Application Based on Molybdenum Trioxide (MoO3)

“…Upon exposure to synthetic air at elevated temperature, the adsorbed oxygen as well as the desorbed H + ions in/out of the sensing layer which returns the absorbance spectrum to its original baseline. The stoichiometry of the MoO3 is restored from Mo 5+ to Mo 6+ [22].…”

“…The MoO 3 coated based sensor had a highly NH 3 absorption response but a substantially lower response for the other gases. Furthermore, the adsorption of MoO 3 based materials was highly selective for polar molecules such as NH 3 , whereas sensitivity was low for non-polar molecules such as H 2 and CH 4 [22].…”

Room-temperature growth optimization and PL characteristic of polytype h/α-MoO3 thin films by chemical precipitation method

“…Molybdenum trioxide is a wide-bandgap (2.7 to 3.2 eV) n-type semiconductor [3]. It has numerous applications as in organic electrochromic devices [8], light-emitting diodes (OLEDs) [9], Li-ion batteries [10], solar cells [11], field emission [5], supercapacitors [12], photocatalysis [13,14], and gas sensors [6,[15][16][17][18][19].…”